JP7764141B2 - Bale molded product of rubber composition, method for manufacturing bale molded product, rubber composition for crosslinking, and tire tread - Google Patents

Description

The present invention relates to a bale molded product of a rubber composition, a method for producing a bale molded product, a rubber composition for crosslinking, and a tire tread.

In recent years, in the fields of rubber materials for tire treads, sheets, films, and asphalt modification, rubber compositions containing rubbery polymers with ethylene structures and crosslinkable unsaturated groups have been proposed for the purpose of increasing mechanical strength and compression set (see, for example, Patent Documents 1 to 3).

International Publication No. 2019/151126 International Publication No. 2019/151127 International Publication No. 2019/078083

However, the previously proposed rubber compositions containing rubbery polymers having an ethylene structure and incorporating crosslinkable unsaturated groups as described above have problems such as molded articles of the rubber composition easily undergoing cold flow and changing shape, thermal degradation of the rubber composition during production, easy contamination of molding dies, easy peeling of the rubber composition from the bale molded article, and difficulty in adhering packaging sheets to the bale molded article.

The object of the present invention is to provide a bale molded product of a rubber composition that is resistant to cold flow and thermal degradation.

The present inventors have conducted extensive research and investigation to solve the problems of the prior art described above, and as a result have discovered that by specifying the aluminum content within a predetermined range in a bale molded product made of a rubber composition containing a rubbery polymer of a specific structure, the bale molded product is less likely to cold flow and less likely to undergo thermal degradation during production, which has led to the completion of the present invention.
That is, the present invention is as follows.

[1]
a rubbery polymer (A) having an iodine value of 10 to 250, an ethylene structure of 3% by mass or more, and a vinyl aromatic monomer block of less than 10% by mass;
Aluminum (B),
a metal (C) from Group 3 and/or Group 4 of the periodic table;
Contains
40 ppm≦aluminum (B) content≦200 ppm;
The content of metals (C) of Group 3 and/or 4 of the periodic table is 61 ppm or less,
the rubber-like polymer (A) is a hydrogenated product of a conjugated diene polymer, and has a vinyl aromatic monomer unit content of 5% by mass or more, and a modification rate measured by a column adsorption GPC method of 40% by mass or more;
A method for producing a bale molded product of a rubber composition, comprising:
polymerizing the conjugated diene polymer in a solution;
adding aluminum (B) and a metal (C) of Group 3 and/or Group 4 of the periodic table to the solution containing the conjugated diene-based polymer;
thereafter, hydrogenating the conjugated diene-based polymer to obtain the rubber composition containing the rubbery polymer (A) ;
molding the rubber composition;
A method for producing a bale molded body, comprising:
[2]
The method for producing a bale molded product according to [1] above, wherein the rubber-like polymer (A) contains a nitrogen atom.
[3]
The method for producing a bale molded product according to [1] or [2] above, wherein the rubber composition further contains 30% by mass or less of a rubber softener (D).
[4]
The method for producing a bale molded article according to any one of [1] to [3] , wherein the rubber composition contains 0.05% by mass or more and 1.5% by mass or less of water.
[5]
The method for producing a bale molded product according to any one of [1] to [4] , wherein the rubber composition contains 2 ppm to 60 ppm of lithium.
[6]
The method for producing a bale molded body according to any one of [1] to [5] above, wherein 90 mass % or more of the aluminum (B) is aluminum oxide and/or aluminum hydroxide.
[7]
The method for producing a bale molded product according to any one of [1] to [6] above, further comprising a step of removing the solvent from the solution containing the rubbery polymer (A) by steam stripping.

The present invention makes it possible to obtain a bale molded product made from a rubber composition that is resistant to cold flow and thermal degradation.

Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail.
It should be noted that the following embodiments are merely examples for explaining the present invention, and the present invention is not limited to the following embodiments. The present invention can be practiced by appropriately modifying it within the scope of its gist.

[Bale molded product of rubber composition]
The bale molded article of the rubber composition of this embodiment is
a rubbery polymer (A) having an iodine value of 10 to 250, an ethylene structure of 3% by mass or more, and a vinyl aromatic monomer block of less than 10% by mass;
Aluminum (B),
Contains
The bale molded article of the rubber composition has an aluminum (B) content of 2 ppm≦200 ppm.
By having the above-mentioned constitution, it is possible to obtain a bale molded article of a rubber composition that is resistant to cold flow and thermal deterioration during production, storage and processing.

(Rubber polymer (A))
The rubber-like polymer (A) contained in the rubber composition constituting the bale molded article of this embodiment (hereinafter referred to as the rubber composition of this embodiment) is a rubber-like polymer having an iodine value of 10 to 250, an ethylene structure content of 3% by mass or more, and a vinyl aromatic monomer block content of less than 10% by mass.

<Iodine value>
The rubber-like polymer (A) constituting the rubber composition of this embodiment has an iodine value of 10 to 250.
From the viewpoint of ease of crosslinking, the iodine value is 10 or more, preferably 15 or more, more preferably 30 or more, even more preferably 50 or more, and even more preferably 70 or more.
On the other hand, from the viewpoint of the weather resistance of the rubbery polymer (A), it is 250 or less, preferably 200 or less, more preferably 150 or less, even more preferably 110 or less, and even more preferably 80 or less.
The iodine value can be measured in accordance with the method described in "JIS K 0070:1992".
The iodine value is a value that represents the amount of halogen that reacts with 100 g of a target substance converted into the number of grams of iodine, and therefore the unit of the iodine value is "g/100 g."
Since the conjugated diene monomer unit has a double bond, in the production method of the rubbery polymer (A) described below, for example, when a conjugated diene monomer and a vinyl aromatic monomer are copolymerized, the rubbery polymer (A) will have a lower iodine value as the content of the conjugated diene monomer unit is lower, and further, when the conjugated diene monomer is hydrogenated, the iodine value will be lower as the hydrogenation rate is higher.
The iodine value of the rubbery polymer (A) can be controlled within the above-mentioned range by adjusting the polymerization conditions such as the amount of the conjugated diene monomer having an unsaturated bond added, the polymerization time, and the polymerization temperature, and the amount of hydrogen added in the hydrogenation step, the hydrogenation time, and other conditions.

<Content of ethylene structure>
The rubbery polymer (A) constituting the rubber composition of the present embodiment has an ethylene structure content of 3% by mass or more.
When the ethylene structure is 3% by mass or more, the mechanical strength is excellent, and the ethylene structure is preferably 5% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more.
The ethylene structure content is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.
When the ethylene structure is 90% by mass or less, the rubber composition of the present embodiment has excellent moldability into a sheet-like or block-like molded article and excellent rubber elasticity.
The ethylene structure in the rubbery polymer (A) includes various forms, such as an ethylene structure obtained by copolymerizing an ethylene monomer, an ethylene structure obtained by polymerizing a conjugated diene monomer and then hydrogenating it, etc. For example, when a 1,4-butadiene unit is hydrogenated, two ethylene structures are obtained, and when a 1,4-isoprene unit is hydrogenated, one propylene structure and one ethylene structure are obtained.
The content of the ethylene structure in the rubbery polymer (A) can be measured by the method described in the Examples below, and can be controlled to fall within the above-mentioned range by adjusting the amount of ethylene added, the amount of conjugated diene monomer added, the hydrogenation rate, etc.

<Vinyl aromatic monomer block content>
The rubber-like polymer (A) has a vinyl aromatic monomer block content of less than 10% by mass (vinyl aromatic monomer block <10% by mass).
The vinyl aromatic monomer block refers to a block in which eight or more vinyl aromatic monomer units are chained.
When the vinyl aromatic monomer block content is less than 10% by mass, the rubber composition of this embodiment tends to have excellent moldability into bale molded articles and excellent cuttability during weighing of the bale molded articles. The vinyl aromatic monomer block content is preferably 7% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.
From the viewpoint of flexibility of the rubber-like polymer or rubber composition, it is preferable that the vinyl aromatic monomer block has few or no blocks in which 30 or more vinyl aromatic monomer units are chained.
Specifically, when the polymer constituting the rubbery polymer (A) is a butadiene-styrene copolymer, the content of the vinyl aromatic monomer block can be measured by decomposing the polymer by the Kolthoff method (the method described in I.M. KOLTHOFF, et al., J. Polym. Sci. 1, 429 (1946)) and analyzing the amount of polystyrene insoluble in methanol. As another method, it can be measured by a known method such as measuring the chain of styrene units using NMR, as described in WO 2014-133097.
The vinyl aromatic monomer block content of the rubbery polymer (A) can be controlled within the above-mentioned range by adjusting the method of adding the vinyl aromatic monomer, the addition of a polymerization aid, the polymerization temperature, etc.

<Monomer units that cause the rubber polymer (A) to contain an unsaturated group>
The rubbery polymer (A) preferably contains 2 mass% or more of conjugated diene monomer units or monomer units having an unsaturated group such as myrcene, etc. From the viewpoints of economy and productivity, it is more preferable that the rubbery polymer (A) contains conjugated diene monomer units.
The conjugated diene monomer units and myrcene contained as components of the rubbery polymer (A) have double bonds, and therefore act as crosslinkable unsaturated groups.
The content of conjugated diene monomer units and monomer units having an unsaturated group such as myrcene in the rubbery polymer (A) is closely related to the above-mentioned iodine value.
When the content of conjugated diene monomer units or monomer units having an unsaturated group such as myrcene in the rubbery polymer (A) is 2% by mass or more, it is excellent in terms of ease of crosslinking.
The content of the conjugated diene monomer unit in the rubbery polymer (A) is more preferably 3% by mass or more, and even more preferably 6% by mass or more.
The content of conjugated diene monomer units and monomer units having an unsaturated group such as myrcene is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, in which case weather resistance and resistance to deterioration over time are excellent.
The content of the conjugated diene monomer units and the monomer units having an unsaturated group such as myrcene in the rubbery polymer (A) can be measured by the method described in the Examples below, and can be controlled to fall within the above-mentioned numerical range by adjusting the amount of the conjugated diene monomer units and the monomers having an unsaturated group such as myrcene added or the hydrogenation rate of the conjugated diene monomer, which will be described later.

(Aluminum (B))
The rubber composition of the present embodiment contains aluminum (B), and the content of aluminum (B) in the rubber composition is 2 ppm≦aluminum (B)≦200 ppm.
The aluminum content (B) in the rubber composition of this embodiment is 2 ppm or more, preferably 4 ppm or more, more preferably 6 ppm or more, and even more preferably 10 ppm, from the viewpoint of the cold flow properties of a bale molded product of the rubber composition.
On the other hand, from the viewpoint of the heat degradation resistance of the rubber composition of the present embodiment, the content is 200 ppm or less, preferably 80 ppm or less, more preferably 40 ppm or less, and even more preferably 25 ppm or less.
The reason why the inclusion of aluminum (B) can suppress cold flow is thought to be that the aluminum-containing compound is dispersed in the form of fine particles, and in the process of being dispersed into fine particles, it becomes entangled with the molecules of the rubber-like polymer (A), thereby acting as physical crosslinking points in the rubber composition and suppressing cold flow.
The aluminum content of the rubber composition of the present embodiment can be measured by the method described in the Examples below, and can be controlled to fall within the above-mentioned numerical range by adjusting the type and amount of polymerization catalyst or hydrogenation catalyst, deashing, or conditions for the solvent removal step described below.

(Preferred Structure of Rubber Polymer (A))
<Hydrogenated polymer>
The rubber-like polymer (A) is preferably a hydrogenated polymer obtained by hydrogenating (hydrogenating) a part or most of the double bonds in a conjugated diene-based polymer obtained by polymerizing or copolymerizing at least a conjugated diene monomer, and more preferably a hydrogenated product of a copolymer obtained by copolymerizing at least ethylene and a conjugated diene monomer.
The unsaturated group in the rubbery polymer (A) preferably contains a conjugated diene monomer unit. That is, in the production process of the rubbery polymer (A), when at least a conjugated diene monomer is polymerized or copolymerized and then a part or most of the double bonds in the polymer are hydrogenated (hydrogenated), it is preferable that the conjugated diene monomer units remaining unhydrogenated are contained among the conjugated diene monomer units so as to achieve a predetermined iodine value, and when at least ethylene and a conjugated diene monomer are copolymerized, it is preferable that the polymer contains conjugated diene monomer units so as to achieve a predetermined iodine value.
The hydrogenation rate and the inter- or intra-molecular distribution of monomers such as ethylene, conjugated diene monomers, and vinyl aromatic monomers in the rubbery polymer (A) are not particularly limited, and may be uniform, non-uniform, or distributed.
The rubbery polymer (A) contained in the bale molded product of the rubber composition of this embodiment is preferably a hydrogenated random copolymer from the viewpoints of the handleability of the bale molded product and the tensile properties, heat resistance, and weather resistance when crosslinked. Specifically, when a hydrogenated random copolymer is used as the bale molded product, it is superior to a block copolymer in terms of bale crushability.

<Vinyl aromatic monomer unit content>
The rubbery polymer (A) preferably has a vinyl aromatic monomer unit content of 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and even more preferably 20% by mass or more, from the viewpoints of deformation resistance of the bale molded article during transportation and breaking strength and wet skid resistance when used in a tire tread.
On the other hand, from the viewpoints of cuttability during weighing of the bale molded body, the resistance to aggregation of the rubbery polymer in the solvent removal step, ease of adjusting the metal content in the rubber composition, and fuel economy and abrasion resistance when used in a tire tread, the content of vinyl aromatic monomer units in the rubbery polymer (A) is preferably 45% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less.
When a high modulus is required, such as in a run-flat tire component, the content is preferably 30% by mass or more.
The content of the vinyl aromatic monomer units in the rubbery polymer (A) can be measured by the method described in the Examples below, and can be controlled to fall within the above-mentioned range by adjusting the amount of the vinyl aromatic monomer added in the polymerization step.

(Aluminum (B) in Rubber Composition)
The aluminum (B) in the rubber composition of the present embodiment is preferably a catalyst residue from the production of the rubbery polymer (A).
When the rubbery polymer (A) is a rubbery polymer obtained by polymerizing a conjugated diene monomer and then hydrogenating the polymer, the aluminum (B) is preferably a residue of a hydrogenation catalyst component used in the production. When the rubbery polymer (A) is a rubbery polymer obtained by copolymerizing ethylene and a conjugated diene monomer, the aluminum (B) is preferably a residue of a polymerization catalyst component used in the production.
Furthermore, from the viewpoints of resistance to coloration and ease of drying in the production process, the aluminum (B) in the rubber composition of the present embodiment is preferably 80 mass % or more in the form of aluminum oxide and/or aluminum hydroxide, more preferably 85 mass % or more, and even more preferably 90 mass % or more.

From the viewpoint of easily controlling the amount of metal in the rubber composition to the desired value, the hydrogenation catalyst component used in producing the rubbery polymer (A) is preferably a mixture or reaction product of a titanium compound and an aluminum compound, as described in, for example, JP-A Nos. 1-275605, 2-172537, 4-96904, 8-33846, 8-41081, WO 2014-046016, 2014-046017, 2014-065283, 2017-090714, or WO 2017-090714.

Examples of the Ti compound include titanocene of the following formula (1):

(In the formula (1), R ₁ and R ₂ represent a group selected from the group consisting of a C1 to C12 hydrocarbon group, an aryloxy group, an alkoxyl group, a halogen group, and a carbonyl group, and R ₁ and R ₂ may be the same or different.)

From the viewpoint of a high hydrogenation rate, the Ti compound is not limited to the following, but preferred examples include bis(η5-cyclopentadienyl)titanium di(p-tolyl), bis(η5-cyclopentadienyl)titanium di(phenyl), bis(η5-cyclopentadienyl)titanium di(3,4-xylyl), bis(η5-cyclopentadienyl)titanium(furfuryloxy)chloride, and bis(η5-cyclopentadienyl)titanium dichloride.
From the viewpoint of economy, bis(η5-cyclopentadienyl)titanium dichloride is more preferred.

The aluminum compound is not limited to the following, but preferred examples include trimethylaluminum, triethylaluminum, triisobutylaluminum, tripentylaluminum, trihexylaluminum, triphenylaluminum, diethylaluminum chloride, dimethylaluminum chloride, ethylaluminum dichloride, methylaluminum sesquichloride, ethylaluminum sesquichloride, diethylaluminum hydride, diisobutylaluminum hydride, triphenylaluminum, tri(2-ethylhexyl)aluminum, (2-ethylhexyl)aluminum dichloride, methylaluminoxane, diisobutylaluminum hydride, and ethylaluminoxane.
Furthermore, from the viewpoint of enhancing the activity of the hydrogenation catalyst and controlling the aluminum content, it is preferable to use trimethylaluminum and/or triethylaluminum as the aluminum compound. By selecting trimethylaluminum and/or triethylaluminum as the aluminum compound, the efficiency as a cocatalyst for the hydrogenation reaction is high, and further, the titanium/aluminum content ratio in the polymerization solution can be advantageously easily controlled.

As the polymerization catalyst component used in producing the rubbery polymer (A), from the viewpoint of easily controlling the amount of metal in the rubber composition of the present embodiment to a desired value, for example, a mixture of a compound having a lanthanoid element and an aluminum compound described in WO 2019/078083, WO 2019/111496, WO 2019/142501, WO 2019/171679, and WO 2019/216100 is preferred.
Among the lanthanoid elements, rare earth element compounds, such as gadolinium compounds, are preferred.
The gadolinium compound is preferably a rare earth element compound represented by the following formula (2), in which M in formula (2) is gadolinium.

In the rare earth element compound represented by the formula (2), M is at least one element selected from the group consisting of lanthanoid elements, scandium, and yttrium, and NQ ¹ , NQ ² , and NQ ³ are amino groups, and may be the same or different.
However, the formula (2) is a compound having an M—N bond.

The rare earth element compound represented by the formula (2) is composed of a compound having three M—N bonds.
By having three M—N bonds, each bond is chemically equivalent, making the structure stable.
In the formula (2), the amide group represented by NQ is not limited to the following, but examples thereof include aliphatic amide groups such as a dimethylamide group, a diethylamide group, and a diisopropylamide group; aryl amide groups such as a phenylamide group, a 2,6-di-tert-butylphenylamide group, a 2,6-diisopropylphenylamide group, a 2,6-dineopentylphenylamide group, a 2-tert-butyl-6-isopropylphenylamide group, a 2-tert-butyl-6-neopentylphenylamide group, a 2-isopropyl-6-neopentylphenylamide group, and a 2,4,6-tert-butylphenylamide group; and bistrialkylsilylamide groups such as a bistrimethylsilylamide group.
As the rare earth element compound represented by the formula (2), tris[bis(trimethylsilyl)amido]gadolinium (Gd[N(Si(CH ₃ ) ₃ ) ₂ ] ₃ ) is preferred from the viewpoint of a high polymerization rate.

The aluminum compounds constituting the polymerization catalyst component include the same aluminum compounds as those in the hydrogenation catalyst described above.

The aluminum compound such as the catalyst component described above added during the production of the rubber polymer (A) is preferably 300 ppm or less, more preferably 200 ppm or less, even more preferably 100 ppm or less, and even more preferably 80 ppm or less, in terms of the heat degradation resistance of the rubber composition of this embodiment, the oxidative degradation resistance of the bale molded article, and economic efficiency, in terms of aluminum metal equivalent.
Regarding the amount of catalyst component added during the production of the rubbery polymer (A), the higher the reaction temperature, the faster the reaction rate, but if the reaction temperature is increased, the amount added must be increased in consideration of the deactivation of the catalyst component, and the amount of metal in the rubber composition increases. Therefore, in order to reduce the amount of metal in the rubber composition of this embodiment, from the viewpoint of reducing the amount of catalyst component added, the reaction temperature is preferably 100°C or less, and more preferably 90°C or less.

(Metals, nitrogen atoms, etc. in rubber composition)
The rubber composition of the present embodiment preferably contains, as a metal other than aluminum, a metal (C) of Group 3 and/or Group 4 of the periodic table in an amount of 120 ppm or less.
From the viewpoint of contamination resistance of a molding die when molding the rubber composition of this embodiment, the content is preferably 3 ppm or more, more preferably 10 ppm or more, and even more preferably 15 ppm or more.
The reason why the presence of a metal (C) from Group 3 and/or 4 of the periodic table can suppress contamination of the molding die is thought to be that the presence of metal particles on the contact surface with the die reduces adhesion of the polymer to the die, similar to the effect of baby powder.
On the other hand, from the viewpoint of the difficulty of peeling the rubber composition from the bale molded body and the adhesion of the packaging sheet to the bale molded body, the content is preferably 120 ppm or less, more preferably 100 ppm or less, even more preferably 50 ppm or less, and even more preferably 30 ppm or less.
By setting a preferred upper limit for the content of the metal (C) of Group 3 and/or Group 4 of the periodic table, it is possible to prevent the rubber composition from becoming brittle due to the presence of too many metal particles, and to obtain the effect of suppressing peeling of the rubber composition.

The metal (C) of Group 3 and/or Group 4 of the periodic table contained in the rubber composition is preferably a residue of a hydrogenation catalyst or a polymerization catalyst used in producing the rubbery polymer (A). The metal (C) of Group 3 and/or Group 4 of the periodic table is the total amount of the metal of Group 3 and the metal of Group 4 of the periodic table, or the total amount of the metal of Group 3 or the metal of Group 4 of the periodic table.
Metals in Group 3 of the periodic table include scandium (Sc), yttrium (Y), lanthanides (La-Lu), and actinides (Ac-Lr).
Furthermore, examples of metals in Group 4 of the periodic table include titanium, zirconium, hafnium, and rutherfordium. These metals are preferably used as components of hydrogenation catalysts and polymerization catalysts. Furthermore, lanthanides from Group 3 of the periodic table are more preferable, and gadolinium is even more preferable. Titanium is more preferable as a Group 4 element of the periodic table.

From the viewpoints of the production cost of the rubber polymer (A), fuel economy and flexibility when used in a tire, and the degree of freedom in the structure that can be produced, it is preferable that the rubber polymer (A) be obtained by polymerizing a conjugated diene monomer and then hydrogenating the polymer.
That is, the polymerization step contains a metal based on the polymerization catalyst, and the hydrogenation step contains a metal based on the hydrogenation catalyst.

The rubber composition of the present embodiment may contain lithium as a metal other than aluminum.
The lithium content in the rubber composition of this embodiment is preferably 60 ppm or less, more preferably 50 ppm or more, even more preferably 40 ppm or less, and even more preferably 30 ppm or less, from the viewpoint of color change resistance of the rubber composition.
On the other hand, from the viewpoint of tensile elongation after crosslinking, the concentration is preferably 2 ppm or more, more preferably 5 ppm or more, and even more preferably 10 ppm or more.
After the hydrogenation step, adjusting the conditions for the steps of removing the solvent from the solution and drying affects the content of aluminum (B) and the content of lithium. Therefore, it is a preferred embodiment to set the conditions for the steps of removing the solvent and/or drying so that the content of lithium falls within a preferred range, and by adjusting the conditions for the steps of removing the solvent and/or drying, the content of lithium can be controlled within the above-mentioned numerical range.

The content of the metal (C) from Group 3 and/or 4 of the periodic table and lithium can be controlled by adjusting the amount of the lithium-containing polymerization initiator, hydrogenation catalyst, or polymerization catalyst added, and the conditions for the step of removing the solvent from the polymerization solvent, which will be described later.

Setting the reaction temperature high increases the reaction rate, which is preferable from the perspective of increasing production efficiency. However, because the polymerization initiator, polymerization catalyst, and hydrogenation catalyst are all easily deactivated at high temperatures, setting the reaction temperature high tends to require increasing the amounts of polymerization initiator, polymerization catalyst, and/or hydrogenation catalyst to be added, taking into account the amount of deactivation. In light of this, in order to reduce the amount of lithium contained in the rubber composition of this embodiment, it is preferable to set the reaction temperature low, reduce the amount of deactivation, and adjust the amount to be added. Specifically, the reaction temperature is preferably 100°C or lower, and more preferably 90°C or lower.

The content of aluminum (B) and the content of metal (C) of Group 3 and/or Group 4 of the periodic table in the rubber composition of this embodiment refers to the amount of each element.
Aluminum (B) and metals (C) of Group 3 and/or Group 4 of the periodic table, which are residues of hydrogenation catalysts and polymerization catalysts, are finely dispersed in the rubber composition and turn into metal compounds or complexes that are difficult to identify, which may affect the physical properties of the rubber composition.
With regard to the particle size of the metal, metal compound, and composite in the rubber composition of this embodiment, from the viewpoint of a balance of properties such as preventing contamination of the molding die, preventing peeling of the rubber composition from the bale molded body, and improving the smoothness when the rubber composition for crosslinking is made into a sheet, it is preferable that 60 vol% or more of the total volume of the particles (100 vol%) be 0.1 to 100 μm.More preferably, 80 vol% or more are in the above numerical range.
The particle size of the metal, metal compound, and composite in the rubber composition can be measured by dissolving the rubber composition containing the metal, metal compound, or composite in an inert solvent and analyzing the resulting polymer solution with a laser diffraction particle size distribution analyzer.

From the viewpoints of the peel resistance of the rubber composition from the bale molded product and the fuel economy when made into a tire, the rubber-like polymer (A) preferably contains a tin atom or a nitrogen atom. It is more preferable that it contains a nitrogen atom.

From the viewpoint of dispersibility of silica when producing a tire using silica, the rubbery polymer (A) preferably has a modification rate of 40% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, as measured by a column adsorption GPC method.
In this specification, the "modification ratio" represents the mass ratio of the polymer having a nitrogen atom-containing functional group to the total amount of the rubbery polymer (A).
The position at which the nitrogen atom is introduced into the rubbery polymer (A) may be any of the polymerization initiation terminal of the rubbery polymer (A), in the molecular chain (including the graft product), or at the polymerization terminal.

When the rubbery polymer (A) is a hydrogenated conjugated diene polymer, from the viewpoints of polymerization productivity, a high modification rate, and the wear resistance and fuel economy of the resulting tire, it is preferable to use a coupling agent containing tin or nitrogen atoms to introduce tin or nitrogen atoms into the rubbery polymer (A), and it is more preferable to use a coupling agent containing nitrogen atoms to introduce nitrogen.

As the nitrogen atom-containing coupling agent, from the viewpoints of polymerization productivity and a high modification rate, an isocyanate compound, an isothiocyanate compound, an isocyanuric acid derivative, a nitrogen group-containing carbonyl compound, a nitrogen group-containing vinyl compound, a nitrogen group-containing epoxy compound, a nitrogen group-containing alkoxysilane compound, and the like are preferred.
As these nitrogen atom-containing coupling agents, nitrogen group-containing alkoxysilane compounds are more preferred from the viewpoints of polymerization productivity of the rubber polymer (A), a high modification rate, and tensile strength when made into a tire.

Examples of the nitrogen group-containing alkoxysilane compound include, but are not limited to, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, and 2,2-dimethoxy-1-(5-trimethoxysilylpentyl). -1-aza-2-silacycloheptane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy,2-methyl-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-ethoxy,2-ethyl-1-(3-triethoxysilylpropyl)-1-aza-2-silacyl cyclopentane, 2-methoxy, 2-methyl-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, and 2-ethoxy, 2-ethyl-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane, tris(3-trimethoxysilylpropyl)amine, tris(3-methyldimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-methyldiethoxysilylpropyl) amine, tris(trimethoxysilylmethyl)amine, tris(2-trimethoxysilylethyl)amine, and tris(4-trimethoxysilylbutyl)amine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, and N ¹ -(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N ¹ -methyl-N ³ -(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N ³ -(3-(trimethoxysilyl)propyl)-1,3-propanediamine.

When the rubber-like polymer (A) is produced by copolymerizing ethylene and a conjugated diene monomer, the rubber composition of this embodiment has the advantage that the amount of metal contained can be easily controlled to a desired value.
Furthermore, from the viewpoint of fuel economy, abrasion resistance, and flexibility when the rubber composition of the present embodiment is used in a tire, it is preferable that the rubber-like polymer (A) contains at least one of a tin atom, a nitrogen atom, and a silicon atom.
From the viewpoint of the productivity of the rubbery polymer (A), it is preferable to carry out a method of introducing at least one of a tin atom, a nitrogen atom, and a silicon atom using a coupling agent containing a tin atom, a nitrogen atom, or a silicon atom when the conversion rate of the polymerization reaction reaches 100%.
Examples of coupling agents containing a tin atom, a nitrogen atom, or a tin atom include, but are not limited to, tin-containing compounds such as bis(1-octadecylmaleate)dioctyltin, isocyanate compounds such as 4,4-diphenylmethane diisocyanate, and alkoxysilane compounds such as glycidylpropyltrimethoxysilane.

(Physical Properties of Rubber Polymer (A) and Rubber Composition)
<Glass transition temperature>
The glass transition temperature of the rubbery polymer (A) is preferably −90° C. or higher, more preferably −80° C. or higher, and even more preferably −75° C. or higher, from the viewpoint of tensile strength when made into a tire.
On the other hand, from the viewpoint of the cut resistance of the sheet during tire production and the flexibility of the tire when made into a tire, the temperature is preferably −15° C. or lower, more preferably −30° C. or lower, and even more preferably −40° C. or lower.
The glass transition temperature is determined in accordance with ISO 22768:2006 by recording a DSC curve while increasing the temperature within a predetermined temperature range, and the peak top (inflection point) of the DSC differential curve is taken as the glass transition temperature.

<Weight average molecular weight>
The weight average molecular weight of the rubber polymer (A) is preferably 150,000 or more, and more preferably 200,000 or more, from the viewpoints of the shape stability of the bale molded product of the rubber composition of this embodiment and the tensile strength and abrasion resistance of the crosslinked product using the rubber composition.
On the other hand, from the viewpoint of processability when the rubber composition is made into a rubber composition for crosslinking, the molecular weight is preferably 1,000,000 or less, more preferably 600,000 or less, and even more preferably 500,000 or less.
The molecular weight distribution (=weight average molecular weight/number average molecular weight) of the rubbery polymer (A) is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.6 or less, from the viewpoint of fuel economy when the rubber composition of the present embodiment is used in a tire.
On the other hand, from the viewpoint of processability when the rubber composition of the present embodiment is made into a rubber composition for crosslinking, the ρ is preferably 1.05 or more, more preferably 1.2 or more, and even more preferably 1.4 or more.
The weight average molecular weight and molecular weight distribution can be calculated from the polystyrene-equivalent molecular weight measured by GPC (gel permeation chromatography), and can be measured by the method described in the examples below.

<Mooney viscosity>
The Mooney viscosity of the rubbery polymer (A) and the rubber composition of this embodiment is an index containing information such as the molecular weight, molecular weight distribution, degree of branching, and content of softener of the rubbery polymer (A).
The Mooney viscosity of the rubber composition of the present embodiment measured at 100°C is preferably 40 or more, more preferably 50 or more, and even more preferably 55 or more, from the viewpoints of abrasion resistance, handling stability, and breaking strength when the rubber composition for crosslinking is used in a tire.
On the other hand, from the viewpoints of productivity of the rubbery polymer (A) and the rubber composition of the present embodiment, and processability when made into a resin composition blended with a filler or the like, it is preferably 170 or less, more preferably 150 or less, even more preferably 130 or less, and even more preferably 110 or less.
The Mooney viscosity can be measured by the method specified in ISO289.

(Rubber softener (D))
The rubber composition of the present embodiment may contain a rubber softener (D) as needed. The content of the rubber softener (D) in the rubber composition of the present embodiment is preferably 30% by mass or less.
In the rubber composition of the present embodiment, the content of the rubber softener (D) is preferably 1 to 30 mass % in order to improve the productivity of the rubber polymer (A) and the processability when an inorganic filler or the like is blended during tire production.
When the molecular weight of the rubber-like polymer (A) is high, for example, when the weight average molecular weight exceeds 1,000,000, the content of the rubber softener (D) is preferably 15 to 30 mass%. On the other hand, when a filler is compounded to prepare a rubber composition, the content of the rubber softener (D) is preferably 1 to 15 mass% from the viewpoint of widening the degree of freedom in the amount of filler compounded. This provides the effect of improving processability during compound preparation.
The content of the rubber softener (D) in the rubber composition of the present embodiment is more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less, from the viewpoint of suppressing deterioration over time when made into a tire.

The rubber softener (D) is not particularly limited, but examples thereof include extender oil, liquid rubber, and resin.
As the rubber softener, extender oils are preferred from the viewpoints of processability, productivity and economy.
The method for adding the rubber softener to the rubber composition of the present embodiment is not limited to the following method, but a preferred method is to add the rubber softener (D) to a polymer solution, mix them, and remove the solvent from the resulting polymer solution containing the rubber softener.

Preferred extender oils include, but are not limited to, aromatic oils, naphthenic oils, paraffin oils, and the like.
Among these, from the viewpoints of environmental safety, oil bleeding prevention, and wet grip properties, aroma substitute oils having a polycyclic aromatic (PCA) content of 3 mass% or less according to the IP346 method are preferred. Examples of aroma substitute oils include TDAE (Treated Distillate Aromatic Extracts) and MES (Mild Extraction Solvate) as shown in Kautschuk Gummi Kunststoffe 52(12)799(1999), as well as RAE (Residual Aromatic Extracts).

[Method for manufacturing bale molded body]
The method for producing a bale molded article of this embodiment includes the steps of polymerizing a rubbery polymer (A) in a solution, adding aluminum (B) to the solution containing the rubbery polymer (A) to obtain a rubber composition, and molding the rubber composition.
As described above, aluminum (B) can be contained in the rubber composition by using a catalyst in the polymerization step or a catalyst in the hydrogenation step.

As a method of polymerizing or copolymerizing a conjugated diene monomer and then hydrogenating it, a preferred method involves anionic polymerization of the conjugated diene monomer using various additives and under various conditions, copolymerizing it with other monomers as needed, and then hydrogenating the resulting polymer, as described in WO 96/05250, JP 2000-053706, WO 2003/085010, WO 2019/151126, WO 2019/151127, WO 2002/002663, and WO 2015/006179.

Conjugated diene monomers used in the polymerization process include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. Among these, 1,3-butadiene and isoprene are preferred from the standpoint of ease of industrial availability, with 1,3-butadiene being more preferred. These may be used alone or in combination of two or more.

As the polymerization monomer, a conjugated diene monomer or a monomer other than ethylene can be used as needed.
The other monomer is not particularly limited, but from the viewpoint of mechanical strength when made into a tire, a vinyl aromatic monomer is preferred.
Examples of vinyl aromatic monomers include, but are not limited to, styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, diphenylethylene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, tertiary amino group-containing diphenylethylene (e.g., 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene), etc. Among these, styrene is preferred from the viewpoint of industrial availability.
These may be used alone or in combination of two or more.
As the polymerization monomer, in addition to the conjugated diene monomer and vinyl aromatic monomer, other monomers can be used as needed.
Examples of other monomers include, but are not limited to, unsaturated carboxylic acid esters, unsaturated carboxylic acids, α,β-unsaturated nitrile compounds, α-olefins (butylene, propylene, pentene, hexene, etc.), ethylene, myrcene, ethylidene norbornene, isopropylidene norbornene, cyclopentadiene, and divinylbenzene.

When the rubber-like polymer (A) is a copolymer of ethylene and a conjugated diene monomer, preferred methods for copolymerizing ethylene and a conjugated diene monomer include those described in, for example, WO 2019/078083, WO 2019/171679, and WO 2019/142501. A preferred method involves copolymerizing ethylene, a conjugated diene monomer, and, if necessary, other monomers by coordination polymerization under various additives and conditions.
As the conjugated diene monomer, the above-mentioned conjugated diene monomers can be used.
The other monomer is not particularly limited, but from the viewpoint of the balance of breaking strength, fuel economy, wet skid resistance, and abrasion resistance when used in a tire, it is preferable to contain a vinyl aromatic monomer or a non-conjugated polyene compound monomer.
As the vinyl aromatic monomer, the above-mentioned vinyl aromatic monomers can be used.
As the polymerization monomer, in addition to the conjugated diene monomer, ethylene, and vinyl aromatic monomer, other monomers may be used as required.
As the other monomer, the other monomers described above can be used.

When an aluminum compound is added as a polymerization catalyst or a hydrogenation catalyst during the production of the rubbery polymer (A), the amount of the aluminum compound in terms of metal is adjusted so that the aluminum content in the finally obtained rubbery polymer (A) is 2 ppm or more and 200 ppm or less.
From the viewpoints of improving the polymerizability of the rubbery polymer (A) and facilitating adjustment of the content in steps after polymerization, the amount of the aluminum compound (metal equivalent) added during production of the rubbery polymer (A) is preferably 5 ppm or more and less than 300 ppm, more preferably 20 ppm or more and 250 ppm or less, even more preferably 35 ppm or more and 220 ppm or less, and even more preferably 45 ppm or more and less than 200 ppm.
Furthermore, when a metal compound of Group 3 and/or Group 4 of the periodic table is added as a polymerization catalyst or hydrogenation catalyst during the production of the rubbery polymer (A), the amount of such metal added (metal equivalent amount) is preferably adjusted so that the content of the metal (C) of Group 3 and/or Group 4 of the periodic table in the finally obtained rubbery polymer (A) is in the preferred range of 120 ppm or less, more preferably 3 ppm or more and 120 ppm or less.
From the viewpoints of improving the polymerizability of the rubbery polymer (A) and facilitating adjustment of the content in steps after polymerization, the amount (metal equivalent) of the Group 3 and/or Group 4 metal compound added during production of the rubbery polymer (A) is preferably 6 ppm or more and 200 ppm or less, more preferably 15 ppm or more and 140 ppm or less, and even more preferably 20 ppm or more and 120 ppm or less.

In the production process of the rubbery polymer (A), when hydrogenation is carried out after polymerization or copolymerization of a conjugated diene monomer, the vinyl bond content of the conjugated diene monomer units of the conjugated diene-based polymer before hydrogenation is preferably 10 mol % or more, and more preferably 20 mol % or more, from the viewpoints of productivity of the rubbery polymer (A) and high wet skid resistance when made into a tire.
Furthermore, from the viewpoint of mechanical strength when used in a tire, the content is preferably 75 mol % or less, more preferably 60 mol % or less, even more preferably 45 mol % or less, and even more preferably 30 mol % or less.
The vinyl bond content can be measured by the method described in the examples below.
The polymerization step and the hydrogenation step may each be carried out in a batch or continuous manner.

After the polymerization step of the rubbery polymer (A) or after the hydrogenation step, it is preferable to add a deactivator, neutralizer, etc. to the polymerization solution in order to adjust the metal content in the rubber composition of the present embodiment to a desired range.
The quenching agent is not limited to the following, but examples thereof include water; and alcohols such as methanol, ethanol, and isopropanol.
Examples of the neutralizing agent include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, mainly 10 carbon atoms); aqueous solutions of inorganic acids; and carbon dioxide gas.
After the polymerization step of the rubbery polymer (A), it is preferable to add a rubber stabilizer from the viewpoint of preventing gel formation and improving processing stability.
The rubber stabilizer is not limited to the following, but preferred examples include antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (hereinafter also referred to as "BHT"), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol)propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol.

Various additives may be further added to the rubber composition of the present embodiment as needed.
As additives, fillers or resin components serving as tackifiers, which will be described later, can be added as master batches in a process prior to molding the rubber composition into a bale. In this case, the amount of additive added is preferably 15% by mass or less of the rubber composition.
In the rubber composition of this embodiment, from the viewpoints of making it difficult for the molding die to be contaminated, making it difficult for the rubber composition to peel off from the bale molded body, and making it easy to adhere a packaging sheet to the bale molded body, the content of the rubbery polymer (A) + aluminum (B) + Group 3 and/or Group 4 metal (C) + rubber softener (D) is preferably 85% by mass or more, more preferably 95% by mass or more, and even more preferably 97% by mass or more.

In the process for producing the rubber composition, after the step of polymerizing the rubbery polymer (A) in a solution, the solvent is removed from the polymer solution.
Examples of methods for removing the solvent from the polymer solution include flushing, steam stripping, methods using a drying conveyor after dehydration, a devolatilizing extruder, a drum dryer, and a devolatilizing kneader.
The method using steam stripping is preferred from the viewpoint of small thermal history and easy adjustment of the metal content in the rubber composition to a desired amount. In particular, the method using steam stripping is preferred for the rubber polymer (A) that has been subjected to a coupling reaction using a coupling agent containing a nitrogen atom, since it is difficult to adjust the metal content.
Examples of steam stripping and treatment methods before and after it include methods described in JP-A-10-168101, JP-A-10-204136, WO 2013-146530, and JP-A-2019-131810.

In the manufacturing method of the bale molded body of this embodiment, in the manufacturing process of the rubber composition constituting the bale molded body, it is preferable to carry out a desolvation process in which the solvent is removed from the polymer solution by steam stripping, and a screening process in which the stripping water is separated from the polymer slurry and water-containing crumbs are extracted, as a step prior to the extrusion drying process.
Furthermore, a flushing step may be performed prior to steam stripping to increase the concentration of the solution.
As a preliminary step to the extrusion drying step, a desolvation step is carried out in which the solvent is removed from the polymer solution by steam stripping, thereby obtaining a solvent-free slurry in which porous granular crumbs containing moisture are dispersed in hot water.
By carrying out a screening step in which the stripping water is separated from the polymer slurry and the wet crumbs are taken out, porous granular crumbs containing water can be obtained.
If necessary, it is preferable to carry out a squeezing and dehydrating step in which water is removed using a roll, a screw compression squeezer, etc. By using these dehydrating steps, it is possible to obtain hydrous crumbs with a lower moisture content prior to the extrusion drying step.

A method for achieving the aluminum (B) content requirement of 2 ppm to 200 ppm inclusive in the rubber composition constituting the bale molded article of this embodiment through steam stripping, while also precisely adjusting the lanthanoid element and titanium contents to obtain a rubber composition containing the desired amount of metal residue, preferably involves adjusting the conditions for contacting the solution of the rubbery polymer (A) after polymerization with hot water or steam as follows: Specific examples include adjusting the pressure at which the solution of the rubbery polymer (A) is introduced; adjusting the pressure, temperature, and amount of steam; adding a dispersant such as a phosphate ester or a salt thereof, e.g., polyoxyalkylene alkyl ether phosphate, or a surfactant such as a nonylphenoxy polyethylene glycol phosphate ester or a salt thereof, to the steam; and adjusting the shape and rotation speed of the rotor blades used when mixing the solution of the rubbery polymer (A) after polymerization with hot water or steam.

In the method for producing the rubber composition of this embodiment, from the standpoint of economic efficiency and metal removability, it is preferable to add an alcohol compound as a deactivator to the solution of the rubbery polymer (A), and it is even more preferable to add the above-mentioned dispersants and surfactants that can be added during steam stripping to the rubbery polymer (A) in advance.

Methods for reducing the aluminum (B) content in the rubber composition of this embodiment include adding an alcohol compound as a deactivator to the polymer solution after polymerization in an amount of at least 0.5 times, and preferably at least 1.0 times, the number of moles of rubbery polymer (A); setting the steam/rubbery polymer (A) solution volume ratio in the steam stripping step to at least 0.1, and preferably at least 0.2; lowering the treatment rate; and adding a surfactant to the polymer solution in an amount of at least 100 ppm, and preferably at least 200 ppm, relative to the polymer.

The linear velocity of the rotor in the steam stripping step is preferably in the range of 5 m/s or more and 20 m/s or less, more preferably in the range of 10 m/s or more and 20 m/s or less.
In the process for producing the rubber composition of this embodiment, when 300 ppm or more of aluminum, in terms of metal, is added to the rubbery polymer (A), it is preferable to add 200 ppm or more of a surfactant relative to the rubbery polymer (A) to the rubbery polymer (A) solution, and it is preferable that the rotating blades in the steam stripping step have a linear rotation speed of 15 m/s or more and 20 m/s or less.
In the production process of the rubber composition of this embodiment, when aluminum is added to the rubber polymer (A) in an amount of 200 ppm or more and less than 300 ppm in terms of metal, the rotating blades in the steam stripping step preferably have a linear rotation speed of 10 m/s or more and 20 m/s or less.
In the production process of the rubber composition of this embodiment, when aluminum is added to the rubbery polymer (A) in an amount of less than 200 ppm in terms of metal, it is preferable that the rotor in the steam stripping step has a linear rotation speed of 5 m/s or more and 20 m/s or less, and it is preferable that a surfactant is added to the rubbery polymer (A) solution in an amount of less than 100 ppm relative to the rubbery polymer (A).

After the steam stripping step, it is preferable to carry out extrusion drying and hot air drying steps, as described in, for example, WO 2013-146530.
These allow a porous, granular crumb to be obtained.
The particle size of the crumbs is preferably 0.1 mm or more, and more preferably 0.5 mm or more, from the viewpoint of obtaining resistance to detachment of the rubber composition from the bale molded body and resistance to scattering during drying.
On the other hand, from the viewpoint of the drying property of the remaining solvent and water in the crumb and the expansion resistance of the bale molded body after molding of the rubber composition, the thickness is preferably 30 mm or less, and more preferably 20 mm or less.
The particle size of the crumbs can be adjusted either during the process of removing the solvent and drying, or by processing the produced crumbs.
When adjusting the particle size of the crumbs during the process of removing the solvent and drying the crumbs, for example, methods such as adjusting the molecular weight, composition or structure of the rubbery polymer (A), adjusting the amount of rubber softener (D) added to the solution of the rubbery polymer (A), adjusting the hole diameter of the die of the extrusion dryer, and adjusting the conditions when the solution of the rubbery polymer (A) is poured into hot water to remove the solvent can be mentioned.
When the produced crumbs are processed and adjusted, for example, the crumbs may be sieved or crushed or pulverized in a mixer or granulator.

The specific surface area of the rubbery polymer (A) obtained in the polymerization step or the crumb of the rubber composition of this embodiment is preferably 0.7 to 3.2 ^{m 2} /g, more preferably 1.0 to 3.0 m ² /g, from the viewpoint of handleability.
When the specific surface area of the crumb is 0.7 ^m /g or more, the area in which each crumb adheres to the surrounding crumbs during molding increases, making the crumb less likely to peel off from the molded body.When the specific surface area of the crumb is 3.2 ^m /g or less, the crumb particles are compressed more densely during molding, reducing the voids between the crumbs, thereby suppressing the expansion of the bale molded body.
The method for adjusting the specific surface area of the crumbs to fall within the above range is not particularly limited, but may include, for example, a method in which the crumbs are sieved and the composition of each sieved crumb is adjusted.

From the viewpoint of reducing odor and VOCs, the residual solvent content in the rubber composition of this embodiment is preferably low. It is preferably 5000 ppm or less, more preferably 3000 ppm or less, and even more preferably 1500 ppm or less. Furthermore, from the viewpoint of economy, it is preferably 50 ppm or more, more preferably 150 ppm or more, and even more preferably 300 ppm or more.

(Water content in rubber composition)
The water content in the rubber composition of the present embodiment is preferably 0.05% by mass or more and 1.5% by mass or less.
The water content in the rubber composition is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, from the viewpoint of suppressing gel formation during drying after solvent removal.
On the other hand, from the viewpoint of suppressing condensation and discoloration resistance of the rubber composition, the content is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, and even more preferably 0.8% by mass or less.
The water content in the rubber composition can be controlled within the above-mentioned range by adjusting the particle size of the crumbs, the shape of the crumbs, and the conditions of the drying process.

The bale molded article of this embodiment is a molded article of the rubber composition of this embodiment described above, and is a block-shaped molded article from the viewpoint of handling.
The bale molded body of this embodiment is more preferably a block-shaped molded body of 1,000 cm ^or more, and even more preferably a rectangular parallelepiped bale weighing 17.5 kg to 35 kg.

The method for producing a bale molded article of this embodiment includes a step of molding the rubber composition obtained as described above.
Methods for molding the rubber composition include, for example, compressing crumbs of the rubber composition and preparing sheets of the rubber composition and compressing the sheets one on top of the other, but a particularly preferred method is to prepare crumbs having a specific surface area of 0.7 m ² /g to 3.2 ^{m 2} /g and then compression-molding the crumbs. From the viewpoint of moldability, it is preferable to further carry out a step of sieving the crumbs before molding.
Since the crumbs adhere to each other during compression molding, the specific surface area of the bale molded product is lower than that of the crumbs. The adhesion of the crumbs during compression molding can be controlled by adjusting the molecular weight, composition, and structure of the rubber polymer (A), the rubber softener composition, and the temperature and pressure during compression. For example, when it is desired to increase the adhesion of the crumbs and decrease the specific surface area of the bale molded product, it is preferable to select a method of decreasing the molecular weight of the rubber polymer (A), a method of increasing the amount of the rubber softener, or a method of increasing the temperature and pressure during compression.

From the viewpoint of film packaging properties, the specific surface area of the bale molded body of this embodiment is preferably 0.005 to 0.05 m ² /g, more preferably 0.01 to 0.04 m ² /g. A specific surface area of 0.005 m ² /g or more suppresses bale expansion, while a specific surface area of 0.05 m ² /g or less reduces crumb peeling from the bale molded body, which are preferred.
The specific surface area of the bale molded body can be determined by the BET method.
Generally, the specific surface area of a large-sized bale molded article may vary depending on the position, so it is preferable to measure the rubber composition by sampling it from near the center of the bale molded article.

It is preferable that the crumbs of the rubber composition are sieved according to particle size before being molded into a bale molded article, and then mixed in an appropriate ratio.
If the specific surface area of the bale molded body formed using the crumbs after solvent removal exceeds the upper limit of the above range, it is preferable to increase the composition of large particle size crumbs and decrease the composition of small particle size crumbs among the sieved crumbs, and if the specific surface area of the bale molded body is less than the lower limit of the above range, it is preferable to decrease the composition of large particle size crumbs and increase the composition of small particle size crumbs among the sieved crumbs.

The molding compression pressure for the bale molded body of this embodiment is preferably 3 to 30 MPa, more preferably 10 to 20 MPa. When the molding compression pressure is 30 MPa or less, the molding and compression equipment can be designed compactly, resulting in good installation efficiency. When the molding compression pressure is 3 MPa or more, good moldability is achieved. When moldability is good, the surface of the bale molded body is smooth, there is no peeling of the rubbery polymer (A) after the molding process, and expansion after molding tends to be suppressed.

The temperature of the rubber composition during bale molding is preferably 30 to 120°C, and more preferably 50 to 100°C from the viewpoint of reducing residual solvent and suppressing thermal degradation.
If the temperature of the rubber composition during bale molding is 30°C or higher, moldability is good, while if the temperature is 120°C or lower, gel formation due to thermal degradation of the rubber composition is suppressed, which is preferable.
The higher the temperature and pressure during bale molding, the smaller the specific surface area of the bale molded body.
The pressure retention time during bale formation is preferably 3 to 30 seconds, more preferably 5 to 20 seconds. If the pressure retention time during compression is 30 seconds or less, production efficiency is good, and if it is 5 seconds or more, moldability is good.

The bale molded bodies of this embodiment are preferably wrapped in a resin film (wrapping sheet) to prevent the bale molded bodies from sticking together.
Examples of the resin type of the film include polyethylene, ethylene copolymer resin, polystyrene, high impact polystyrene, and PET.
From the viewpoint of ease of handling during transportation of the bale molded body and preventing condensation from forming in the gap between the packaging sheet and the bale molded body, it is preferable that the packaging sheet has good adhesion.
The bale molded article of this embodiment can be used, for example, for storage in a container for transportation. If the expansion rate of the bale molded article one day after molding is less than 5%, it is preferable because it can be easily stored in the container.

[Rubber composition for crosslinking]
From the viewpoint of high mechanical strength, etc., it is preferable that a crosslinking agent be added to the rubber composition constituting the bale molded article of this embodiment to form a crosslinkable rubber composition, which is then crosslinked to form a crosslinked product and used for various purposes.
The rubber composition for crosslinking of this embodiment contains at least the rubber composition of this embodiment described above and a crosslinking agent, and may further contain other rubber components, fillers, and the like, as necessary.
The other rubbers are not particularly limited and can be appropriately selected depending on the purpose. Examples include styrene-butadiene rubber (emulsion polymerization tire or solution polymerization type), natural rubber, polyisoprene, butadiene rubber, acrylonitrile-butadiene rubber (NBR), chloroprene rubber, ethylene-propylene rubber (EPM), ethylene-propylene-non-conjugated diene rubber (EPDM), butyl rubber, polysulfide rubber, silicone rubber, fluororubber, and urethane rubber.
These may be used alone or in combination of two or more.

In the rubber composition for crosslinking of this embodiment, the content of the rubbery polymer (A) relative to the total amount of rubber components, which is the sum of the rubbery polymer (A) and other rubber components, is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, and even more preferably 80% by mass or more, from the viewpoint of achieving the effects of the present invention.

Furthermore, a filler may be added to the rubber composition for crosslinking of the present embodiment, if necessary, for the purpose of improving reinforcement properties, etc.
The content of the filler in the rubber composition for crosslinking of the present embodiment can be appropriately selected depending on the purpose, but is preferably 10 to 100 parts by mass, more preferably 20 to 80 parts by mass, when the total amount of the rubber components, which is the sum of the rubber-like polymer (A) and other rubber components, is 100 parts by mass.
When the filler content is 10 parts by mass or more, the effect of improving the reinforcing properties due to the blending of the filler can be obtained, and when the filler content is 100 parts by mass or less, it is possible to prevent a significant decrease in fuel efficiency when made into a tire, while suppressing breakage of the molded sheet during processing and ensuring good cohesion of the compound.

The filler to be compounded in the cross-linking rubber composition of the present embodiment is not limited to the following, but examples thereof include carbon black, silica, aluminum hydroxide, clay, alumina, talc, mica, kaolin, glass balloons, glass beads, calcium carbonate, magnesium carbonate, magnesium hydroxide, magnesium oxide, titanium oxide, potassium titanate, barium sulfate, etc. Among these, it is preferable to use carbon black. These may be used alone or in combination of two or more.
The carbon black can be appropriately selected depending on the purpose, and examples thereof include FEF, GPF, SRF, HAF, N339, IISAF, ISAF, SAF, etc. These may be used alone or in combination of two or more.
The nitrogen adsorption specific surface area (N ₂ SA, measured in accordance with JIS K6217-2:2001) of the carbon black can be appropriately selected depending on the purpose.
When the rubber composition for crosslinking of the present embodiment is used as a composition for a fuel-saving tire tread, precipitated silica is preferably used as the filler.

The rubber composition for crosslinking of the present embodiment may contain a silane coupling agent from the viewpoint of improving the dispersibility of the filler and improving the tensile strength of the crosslinked product.
The silane coupling agent has the function of strengthening the interaction between the rubber component and the inorganic filler, and from this viewpoint, it is preferable that the silane coupling agent has a group having affinity or bonding properties for both the rubber component and the inorganic filler, and has a sulfur-bonding moiety and an alkoxysilyl group or silanol group moiety in one molecule.
Such compounds include, but are not limited to, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide, S-[3-(triethoxysilyl)-propyl]octanethioate and condensates of S-[3-(triethoxysilyl)-propyl]octanethioate with [(triethoxysilyl)-propyl]thiol, silanes bearing at least one thiol (—SH) functional group (referred to as mercaptosilanes) and/or at least one masked thiol group.
The content of the silane coupling agent in the rubber composition for crosslinking of this embodiment is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, and even more preferably 1.0 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the filler. When the content of the silane coupling agent is within the above range, the effect of adding the silane coupling agent tends to be more pronounced.

The rubber composition for crosslinking according to the present embodiment contains a crosslinking agent. The crosslinking agent can be appropriately selected depending on the purpose, and examples thereof include sulfur-based crosslinking agents, organic peroxide-based crosslinking agents, inorganic crosslinking agents, polyamine crosslinking agents, resin crosslinking agents, sulfur compound-based crosslinking agents, and oxime-nitrosamine-based crosslinking agents.
These may be used alone or in combination of two or more.
Among these, sulfur-based cross-linking agents (vulcanizing agents) are more preferred for rubber compositions for tires, and sulfur is even more preferred.

The content of the crosslinking agent in the rubber composition for crosslinking of this embodiment is 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the rubber component. From the viewpoint of high tensile strength and a high crosslinking rate, the content of the crosslinking agent is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.5 parts by mass or more per 100 parts by mass of the rubber component. On the other hand, from the viewpoint of suppressing uneven crosslinking and obtaining high tensile strength, the content is preferably 20 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less.
The rubber component includes the above-mentioned rubbery polymer (A) and other rubber components.

The rubber composition for cross-linking of the present embodiment may contain a vulcanization accelerator in addition to the vulcanizing agent.
Examples of the vulcanization accelerator include guanidine-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, thiuram-based, dithiocarbamate-based, and xanthate-based compounds.

The rubber composition for crosslinking of the present embodiment may contain various additives other than the above-mentioned components, such as other softeners, fillers, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants.
As other softeners, known softeners can be used.
Other fillers include, for example, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate.
Known materials can be used as the heat stabilizer, antistatic agent, weather stabilizer, antioxidant, colorant, and lubricant.

(Method of kneading rubber composition for crosslinking)
The rubber composition for crosslinking of this embodiment can be produced by mixing the rubbery polymer (A) and the crosslinking agent, and, if necessary, various additives such as a silica-based inorganic filler, carbon black or other fillers, a silane coupling agent, and a rubber softener.
The mixing method is not limited to the following, but examples thereof include a melt-kneading method using a general mixer such as an open roll, a Banbury mixer, a kneader, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and a method in which the components are dissolved and mixed and then the solvent is removed by heating.
Among these, the melt kneading method using a roll, a Banbury mixer, a kneader, or an extruder is preferred from the viewpoint of productivity and good kneading properties.
As a mixing method, either a method in which the rubber component, filler, silane coupling agent, and additives are kneaded at once or a method in which they are mixed in several batches can be applied.

[Uses of bale molded body and rubber composition]
The rubber composition constituting the bale molded article of this embodiment can be used for applications such as tire components, interior and exterior parts of automobiles, vibration-proof rubber, belts, footwear, foams, and materials for various industrial products.
Among these, it is preferably used for tire parts.
As tire components, the rubber composition can be used in various tire parts such as treads, carcasses, sidewalls, beads, etc., for example, fuel-efficient tires, all-season tires, high-performance tires, snow tires, studless tires, etc. In particular, the rubber composition of the present embodiment is excellent in abrasion resistance, fuel economy, wet skid resistance, and snow performance, as well as in the balance thereof, when vulcanized, and is therefore suitably used as tire components for tire treads of fuel-efficient tires, high-performance tires, and snow tires.
A conventional method can be used to manufacture a tire. For example, components typically used in tire manufacturing, such as a carcass layer, a belt layer, and a tread layer, each layer comprising at least one selected from the group consisting of an unvulcanized rubber composition for crosslinking and tire cords, are laminated on a tire building drum, and the drum is removed to form a green tire. The green tire is then heated and vulcanized in a conventional manner to manufacture a desired tire (e.g., a pneumatic tire).

Hereinafter, the present embodiment will be described in more detail with reference to specific examples and comparative examples, but the present embodiment is not limited to the following examples and comparative examples.
Various physical properties in the examples and comparative examples were measured by the methods shown below.

[Physical Properties of Rubber Polymer (A) and Rubber Polymer (A) Before Hydrogenation]
(Weight average molecular weight (Mw) of rubbery polymer (A) before hydrogenation)
A chromatogram was measured using a GPC measuring device equipped with three connected columns packed with polystyrene gel, and the weight average molecular weight (Mw) of the rubbery polymer before hydrogenation was determined based on a calibration curve using standard polystyrene.
The eluent used was THF containing 5 mmol/L triethylamine.
The columns used were a guard column manufactured by Tosoh Corporation under the trade name "TSKguard column Super H-H" and columns manufactured by Tosoh Corporation under the trade names "TSKgel Super H5000", "TSKgel Super H6000", and "TSKgel Super H7000".
An RI detector (trade name "HLC8020" manufactured by Tosoh Corporation) was used under conditions of an oven temperature of 40° C. and a THF flow rate of 0.6 mL/min. 10 mg of a sample to be measured was dissolved in 20 mL of THF to prepare a measurement solution, and 20 μL of the measurement solution was injected into a GPC measurement device for measurement.

(Polymer Mooney Viscosity of Rubber Polymer (A) Before Hydrogenation)
The rubber-like polymer before hydrogenation was used as a sample, and the Mooney viscosity was measured in accordance with ISO 289 using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) with an L-type rotor.
The measurement temperature was 100°C.
First, the sample was preheated at the test temperature for 1 minute, and then the rotor was rotated at 2 rpm. The torque after 4 minutes was measured and used as the Mooney viscosity (ML ₍₁₊₄₎ ).

(Modification rate of rubber polymer (A))
The modification rate of the rubbery polymer (A) was measured by a column adsorption GPC method as follows: The measurement was carried out by utilizing the property of a rubbery polymer modified with a nitrogen atom-containing functional group to be adsorbed onto a column.
A sample solution containing a rubber-like polymer and a low-molecular-weight internal standard polystyrene was measured using a polystyrene-based column, and the amount of adsorption onto the silica-based column was measured from the difference between the chromatogram measured using the polystyrene-based column and the chromatogram measured using the silica-based column, and the modification rate was calculated.
Specifically, it is as follows:
Preparation of sample solution:
10 mg of the rubber polymer and 5 mg of standard polystyrene were dissolved in 20 mL of THF (tetrahydrofuran) to prepare a sample solution.
GPC measurement conditions using a polystyrene column:
THF containing 5 mmol/L triethylamine was used as the eluent, and 20 μL of the sample solution was injected into the device and measured. The columns used were a guard column manufactured by Tosoh Corporation under the trade name "TSKguard column Super H-H," and columns manufactured by Tosoh Corporation under the trade names "TSKgel Super H5000,""TSKgel Super H6000," and "TSKgel Super H7000." A chromatogram was obtained using an RI detector (Tosoh Corporation HLC8020) under the conditions of a column oven temperature of 40°C and a THF flow rate of 0.6 mL/min.
GPC measurement conditions using a silica column:
Using a Tosoh Corporation product name "HLC-8320GPC," THF was used as the eluent, 50 μL of the sample solution was injected into the device, and a chromatogram was obtained using an RI detector under the conditions of a column oven temperature of 40 ° C. and a THF flow rate of 0.5 ml / min. The columns used were connected with product names "Zorbax PSM-1000S,""PSM-300S," and "PSM-60S," and a guard column "DIOL 4.6 × 12.5 mm 5 micron" was connected to the front stage.
How to calculate the denaturation rate:
The total peak area of the chromatogram using the polystyrene-based column was set to 100, the peak area of the sample was set to P1, the peak area of the standard polystyrene was set to P2, and the total peak area of the chromatogram using the silica-based column was set to 100, the peak area of the sample was set to P3, and the peak area of the standard polystyrene was set to P4, and the modification rate (%) was calculated using the following formula.
Denaturation rate (%) = [1 - (P2 x P3) / (P1 x P4)] x 100
(However, P1 + P2 = P3 + P4 = 100)

(Bound Styrene Amount of Rubber Polymer (A) Before Hydrogenation)
A measurement sample was prepared by dissolving 100 mg of the rubbery polymer before hydrogenation in 100 mL of chloroform. The amount of bound styrene (mass%) relative to 100 mass% of the rubbery polymer before hydrogenation was measured based on the amount of absorption of ultraviolet light by the phenyl group of styrene at a wavelength (near 254 nm).
Measuring device: A spectrophotometer "UV-2450" manufactured by Shimadzu Corporation was used.

(Microstructure (1,2-vinyl bond content) of butadiene portion of rubber-like polymer (A) before hydrogenation)
As a sample, 50 mg of the rubber-like polymer before hydrogenation was dissolved in 10 mL of carbon disulfide to prepare a measurement sample.
Using a solution cell, an infrared spectrum was measured in the range of 600 to 1000 ^cm , and the microstructure of the butadiene moiety, i.e., the 1,2-vinyl bond content (mol %) was determined from the absorbance at a predetermined wave number according to the calculation formula of Hampton's method (the method described in R.R. Hampton, Analytical Chemistry 21, 923 (1949)).
Measurement device: A Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation was used.

(Amount of styrene block in rubber polymer (A))
A chain consisting of eight or more styrene structural units connected together was defined as a styrene block, and the amount of styrene block was determined as follows.
From the 400 MHz ¹ H-NMR spectrum measured using deuterated chloroform as a solvent, the integral ratio of each chemical shift range in the following (a) was determined to determine the amount of styrene blocks contained in the rubbery polymer.
(a) Aromatic vinyl compound chains of 8 or more: 6.00≦S<6.68

(Iodine value of rubbery polymer (A))
The iodine value of the rubbery polymer (A) was calculated according to the method described in "JIS K 0070:1992".

(Amount of bound styrene (after hydrogenation), amount of ethylene structure, amount of conjugated diene monomer unit of rubber polymer (A))
Using a rubbery polymer as a sample, the amount of bound styrene (after hydrogenation ^{), the amount of ethylene structure, and the amount of conjugated diene monomer units were measured by 1 H} -NMR measurement under the following conditions.
<Measurement conditions>
Measuring equipment: JNM-LA400 (manufactured by JEOL)
Solvent: deuterated chloroform Measurement sample: rubbery polymer Sample concentration: 50 mg/mL
Observation frequency: 400MHz
Chemical shift reference: TMS (tetramethylsilane)
Pulse delay: 2.904 seconds Number of scans: 64 Pulse width: 45°
Measurement temperature: 26℃

[Physical Properties of Rubber Composition]
(Metal Content (Al Amount, Ti Amount) of Rubber Composition)
Using the rubber compositions obtained in the examples and comparative examples described below as samples, the aluminum content (Al content, unit: ppm) and titanium content (Ti content, unit: ppm) in the rubber compositions were measured through elemental analysis using an inductively coupled plasma (ICP, Inductive Coupled Plasma, manufactured by Shimadzu Corporation, device name: ICPS-7510).

(Water content of rubber composition)
50 g of the rubber composition was placed in a hot air dryer heated to 150° C. and dried for 3 hours, and the difference in mass of the rubber composition before and after drying was measured to determine the moisture content of the rubber composition.

[Evaluation of bale molded product of rubber composition]
(Method for removing solvent from rubber composition solution)
<Solvent removal condition 1>
Assuming steam stripping, 20 L of 90°C hot water was placed in a 50 L container, and while stirring at 1000 rpm using a homogenizer (Homomixer MARK II (PRIMIX Corporation, trade name, 0.2 kW)), the rubber polymer solution was added dropwise at a rate of 200 g per minute for 30 minutes, and stirring was continued for 30 minutes even after the end of the dropwise addition to remove the solvent. Crumbs of the rubber composition formed in the hot water were dried to obtain crumbs of the rubber composition.

<Solvent removal condition 2>
Assuming steam stripping, 20 L of 90°C hot water was placed in a 50 L container, and while stirring at a rotation speed of 6000 rpm using a homogenizer (Homomixer MARK II (PRIMIX Corporation, trade name, 0.2 kW)), the rubber polymer solution was added dropwise at a rate of 200 g per minute for 30 minutes, and stirring was continued for 30 minutes even after the end of the dropping to remove the solvent. Crumbs of the rubber composition formed in the hot water were obtained by drying.

<Solvent removal condition 3>
Assuming steam stripping, 20 L of 90°C hot water was placed in a 50 L container, and while stirring at a rotation speed of 12,000 rpm using a homogenizer (Homomixer MARK II (PRIMIX Corporation, trade name, 0.2 kW)), the rubber polymer solution was added dropwise at a rate of 200 g per minute for 30 minutes, and stirring was continued for 30 minutes even after the end of the dropping to remove the solvent. Crumbs of the rubber composition formed in the hot water were obtained by drying.

(Method for molding a bale from a rubber composition)
The crumbs prepared by the above method were heated to 60°C and then filled into a rectangular container having dimensions of 210 mm long side, 105 mm short side, and 200 mm deep, and compressed with a cylinder at a pressure of 3.5 MPa for 10 seconds to obtain a bale molded product of the rubber composition.

(Evaluation: Cold flow property of molded article of rubber composition)
The bale molded under the above conditions was left for 72 hours under a load of 5 kg at an ambient temperature of 25°C and a humidity of 50%, and the thickness (H60) was measured. The thickness change rate (%) was calculated using the following formula.
Thickness change rate (%) = (H0 - H60) x 100/H0
H0 indicates the thickness of the bale immediately after molding.
The smaller the thickness change rate (index), the smaller the cold flow of the rubber bale during storage and the better its handling properties.
If the index was less than 10, it was marked as ⊚; if it was 10 or more but less than 20, it was marked as ◯; if it was 20 or more but less than 40, it was marked as △; and if it was 40 or more, it was marked as ×.
In practice, it must be less than 40, and preferably less than 20.

(Evaluation: Contamination resistance of molding mold)
When 10 bale moldings were performed under the above conditions, the number of times that 5 g or more of metal or crumbs adhered to the rectangular container was evaluated.
If the number of times that metal or crumb adhered was 5g or more in total was 0, it was marked as ◎; if it was 1-2 times, it was marked as ○; if it was 3-4 times, it was marked as △; if it was 5 times or more, it was marked as ×.
In practice, the number of times must be four or less, and two or less is preferable.

(Evaluation: Heat degradation resistance)
The thermal degradation resistance was evaluated by measuring the change in oxidation onset temperature before and after applying a thermal load.
The body temperature of a Labo Plastomill 30C150 (Toyo Seiki Seisakusho) was set to 50°C, 50 g of the rubber composition was added, and the mixture was kneaded at 120 rpm for 5 minutes followed by a 5-minute break, for a total of 3 cycles of kneading.
The oxidation initiation temperatures of the rubber compositions before and after kneading were measured using a thermogravimetric differential thermal analyzer (STA 7200RV, Hitachi).
When the temperature was raised from 30°C to 500°C at a rate of 10°C/min in an atmospheric air, the temperature at which an endothermic peak was confirmed was defined as the oxidation onset temperature, and the difference in the oxidation onset temperature of the rubber composition before and after the application of the thermal load was defined as ΔT and used as an index of heat degradation resistance.
The smaller the ΔT, the better the resistance to heat deterioration and the more suppressed the deterioration of physical properties due to heat, which is preferable.
If ΔT was 0° C. or more and less than 5° C., it was rated as ⊚, if it was 5° C. or more and less than 8° C., it was rated as ◯, if it was 8° C. or more and less than 12° C., it was Δ, and if it was 12° C. or more, it was rated as x. In practice, it needs to be less than 12° C., and it is preferably less than 8° C.

(Evaluation: Peel resistance of rubber composition from molded article)
Using the bale molded under the above conditions, a bale drop test was carried out to determine the amount of crumbs that had fallen off from the bale molded under the above conditions.
Specifically, the bale was dropped vertically from a height of 100 cm onto a concrete floor, and the amount of crumbs that peeled off from the bale was measured.
The smaller the amount of crumbs that peel off, the smaller the amount of crumbs that peel off from the bale molded body after the molding step in the actual bale molded body manufacturing process, so this is preferable.
If this amount was less than 0.05% by mass of the total bale molded body, it was marked with an ⊚; if it was 0.05% by mass or more but less than 0.1% by mass, it was marked with an ◯; if it was 0.01% by mass or more but less than 0.2% by mass, it was marked with a △; and if it was 0.2% by mass or more, it was marked with an ×.
In practice, the content must be less than 0.2% by mass, and preferably less than 0.1% by mass.

(Evaluation: Adhesion of packaging sheet to molded product)
A polyethylene film was adhered to an iron plate, and the bale molded body was placed on the polyethylene film. After leaving it for 72 hours at an ambient temperature of 25°C and humidity of 50% with a load of 5 kg, the adhesion between the polyethylene film and the bale molded body was evaluated.
Specifically, the iron plate was gradually tilted from the state where the bale molded body was left stationary on the iron plate until the angle between the iron plate and the ground was finally 90 degrees, and the iron plate was left stationary in that state.
The following criteria were evaluated: ◎ if the bale did not fall for 10 seconds or more when the angle between the ground and the iron plate was 90 degrees; 〇 if the bale fell for 1 second or more but less than 10 seconds when the angle between the ground and the iron plate was 90 degrees; △ if the bale fell when the angle between the ground and the iron plate was 75 degrees or more but less than 90 degrees, or if it fell in less than 1 second after the angle became 90 degrees; and × if the bale fell when the angle between the ground and the iron plate was 0 degrees or more but less than 75 degrees.
In practice, it is necessary that the angle between the ground and the iron plate be 75 degrees or more so that the bale does not fall.

[Preparation of hydrogenation catalyst, rubbery polymer (A), and rubber composition]
(Preparation of hydrogenation catalyst)
In the examples and comparative examples described later, the hydrogenation catalysts used in preparing rubbery polymers were prepared by the following method.
<Production Example 1>
A nitrogen-purged reaction vessel was charged with 1 liter of dried and purified cyclohexane, and 100 mmol of bis(η5-cyclopentadienyl)titanium dichloride was added. With thorough stirring, an n-hexane solution containing 200 mmol of trimethylaluminum was added, and the mixture was allowed to react at room temperature for approximately 3 days to obtain a hydrogenation catalyst (TC-1).

<Production Example 2>
One liter of dried and purified cyclohexane was placed in a nitrogen-purged reaction vessel, and 100 mmol of bis(η5-cyclopentadienyl)titanium dichloride was added. With thorough stirring, an n-hexane solution containing 300 mmol of trimethylaluminum was added, and the mixture was allowed to react at room temperature for approximately 3 days to obtain a hydrogenation catalyst (TC-2).

<Production Example 3>
A nitrogen-purged reaction vessel was charged with 2 liters of dried and purified cyclohexane, and 40 mmol of bis(η5-cyclopentadienyl)titanium di-(p-tolyl) and 150 g of 1,2-polybutadiene (1,2-vinyl bond content: approximately 85%) having a molecular weight of approximately 1,000 were dissolved therein. Thereafter, a cyclohexane solution containing 60 mmol of n-butyllithium was added to the reaction vessel and reacted at room temperature for 5 minutes. Immediately after this, 40 mmol of n-butanol was added and the mixture was stirred to obtain a hydrogenation catalyst (TC-3).
The resulting catalysts (TC-1) to (TC-3) were stored at room temperature.

(Polymerization of rubbery polymer (A))
<(Polymerization Example 1) Rubber-like polymer (S) before hydrogenation>
A 40 L internal volume autoclave equipped with a stirrer and a jacket and capable of controlling temperature was used as a reactor. 2,160 g of 1,3-butadiene, 300 g of styrene, 21,000 g of cyclohexane, and 30 mmol of tetrahydrofuran (THF) and 4.9 mmol of 2,2-bis(2-oxolanyl)propane as polar substances, from which impurities had been removed in advance, were placed in the reactor, and the internal temperature of the reactor was maintained at 42°C.
As a polymerization initiator, 33.2 mmol of n-butyllithium was fed to the reactor.
After the polymerization reaction started, the temperature inside the reactor began to rise due to heat generated by the polymerization, and after the monomer conversion in the reactor reached 98%, 540 g of 1,3-butadiene was added and reacted.
The temperature inside the reactor finally reached 76°C. Two minutes after the reaction temperature reached this peak, 4.1 mmol of 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (Compound 1) was added to the reactor, and a coupling reaction was carried out for 20 minutes. 15.0 mmol of methanol was added to this polymer solution as a reaction terminator, and a rubbery polymer solution (SS) before hydrogenation was obtained.
A portion of the rubbery polymer solution (SS) before hydrogenation was withdrawn and the solvent was removed in a dryer to obtain a rubbery polymer (S) before hydrogenation.
The analysis results are shown in Table 1.

<(Polymerization Example 2) Rubber-like polymer (T) before hydrogenation>
A temperature-controllable autoclave having an internal volume of 40 L, equipped with a stirrer and a jacket, was used as a reactor. 2,100 g of 1,3-butadiene, 780 g of styrene, 21,000 g of cyclohexane, and 30 mmol of tetrahydrofuran (THF) and 18.3 mmol of 2,2-bis(2-oxolanyl)propane as polar substances, from which impurities had been removed, were placed in the reactor, and the internal temperature of the reactor was maintained at 42°C.
As a polymerization initiator, 26.2 mmol of n-butyllithium was fed to the reactor.
After the polymerization reaction started, the temperature inside the reactor began to rise due to heat generated by the polymerization, and after the monomer conversion in the reactor reached 98%, 120 g of 1,3-butadiene was added and reacted.
The temperature inside the reactor finally reached 78°C. Two minutes after the reaction temperature reached this peak, 3.3 mmol of N,N'-(1,4-phenylene)bis(4-(triethoxysilyl)butan-1-imine) (compound 2) was added to the reactor, and a coupling reaction was carried out for 20 minutes. To this polymer solution, 12.6 mmol of methanol was added as a reaction terminator, and a rubbery polymer solution (TS) before hydrogenation was obtained.
A portion of the rubbery polymer solution (TS) before hydrogenation was withdrawn and the solvent was removed in a dryer to obtain a rubbery polymer (T) before hydrogenation.
The analysis results are shown in Table 1.

<(Polymerization Example 3) Rubber-like polymer (U) before hydrogenation>
A 40 L internal volume autoclave equipped with a stirrer and a jacket and capable of controlling temperature was used as a reactor. 450 g of styrene, 21,000 g of cyclohexane, and 30 mmol of tetrahydrofuran (THF) and 13.1 mmol of 2,2-bis(2-oxolanyl)propane as polar substances, from which impurities had been removed in advance, were placed in the reactor, and the internal temperature of the reactor was maintained at 45°C.
As a polymerization initiator, 26.2 mmol of n-butyllithium was fed to the reactor.
After the polymerization reaction started, the temperature inside the reactor began to rise due to heat generated by the polymerization. After the monomer conversion in the reactor reached 98%, 2,220 g of 1,3-butadiene was added, and 1 minute after the completion of the addition, 120 g of styrene was added and reacted.
The temperature inside the reactor finally reached 78°C. Two minutes after the reaction temperature reached this peak, 3.3 mmol of 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (Compound 1) was added to the reactor, and a coupling reaction was carried out for 20 minutes. 12.6 mmol of methanol was added to this polymer solution as a reaction terminator, and a rubbery polymer solution (US) before hydrogenation was obtained.
A portion of the rubbery polymer solution (US) before hydrogenation was withdrawn and the solvent was removed in a dryer to obtain a rubbery polymer (U) before hydrogenation.
The analysis results are shown in Table 1.

<(Polymerization Example 4) Rubber-like polymer (V) before hydrogenation>
A temperature-controllable autoclave having an internal volume of 40 L, equipped with a stirrer and a jacket, was used as a reactor. 3,000 g of 1,3-butadiene, 21,000 g of cyclohexane, and 30 mmol of tetrahydrofuran (THF) and 4.7 mmol of 2,2-bis(2-oxolanyl)propane as polar substances, from which impurities had been removed in advance, were placed in the reactor, and the internal temperature of the reactor was maintained at 41°C.
As a polymerization initiator, 36.1 mmol of n-butyllithium was fed to the reactor.
After the polymerization reaction began, the temperature inside the reactor began to rise due to heat generated by the polymerization, and the final temperature inside the reactor reached 80°C. Two minutes after the reaction temperature reached this peak, 4.5 mmol of 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (compound 1) was added to the reactor, and a coupling reaction was carried out for 20 minutes. To this polymer solution, 17.3 mmol of methanol was added as a reaction terminator, and a rubbery polymer solution (VS) before hydrogenation was obtained.
A portion of the rubbery polymer solution (VS) before hydrogenation was withdrawn and the solvent was removed in a dryer to obtain a rubbery polymer (V) before hydrogenation.
The analysis results are shown in Table 1.

<(Polymerization Example 5) Rubber-like polymer (W) before hydrogenation>
A temperature-controllable autoclave having an internal volume of 40 L, equipped with a stirrer and a jacket, was used as a reactor. 2,100 g of 1,3-butadiene, 780 g of styrene, 21,000 g of cyclohexane, and 30 mmol of tetrahydrofuran (THF) and 15.1 mmol of 2,2-bis(2-oxolanyl)propane as polar substances, from which impurities had been removed, were placed in the reactor, and the internal temperature of the reactor was maintained at 44°C.
As a polymerization initiator, 20.1 mmol of n-butyllithium was fed into the reactor.
After the polymerization reaction started, the temperature inside the reactor began to rise due to heat generated by the polymerization, and after the monomer conversion in the reactor reached 98%, 120 g of 1,3-butadiene was added and reacted.
The temperature inside the reactor finally reached 79°C. Two minutes after the reaction temperature reached this peak, 1.26 mmol of N,N,N',N'-tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (compound 3) was added to the reactor, and a coupling reaction was carried out for 20 minutes. 10.1 mmol of methanol was added to this polymer solution as a reaction terminator, and a rubbery polymer solution (WS) before hydrogenation was obtained.
A portion of the rubbery polymer solution (WS) before hydrogenation was withdrawn and the solvent was removed in a dryer to obtain a rubbery polymer (W) before hydrogenation.
The analysis results are shown in Table 1.

<(Polymerization Example 6) Rubber-like polymer (X) before hydrogenation>
A 40 L internal volume autoclave equipped with a stirrer and a jacket and capable of controlling temperature was used as a reactor. 2,160 g of 1,3-butadiene, 300 g of styrene, 21,000 g of cyclohexane, and 30 mmol of tetrahydrofuran (THF) and 4.9 mmol of 2,2-bis(2-oxolanyl)propane as polar substances, from which impurities had been removed in advance, were placed in the reactor, and the internal temperature of the reactor was maintained at 42°C.
As a polymerization initiator, 33.2 mmol of n-butyllithium was fed to the reactor.
After the polymerization reaction started, the temperature inside the reactor began to rise due to heat generated by the polymerization, and after the monomer conversion in the reactor reached 98%, 540 g of 1,3-butadiene was added and reacted.
The final temperature inside the reactor reached 76°C. Two minutes after this reaction temperature peak, 4.1 mmol of silicon tetrachloride (Compound 4) was added to the reactor, and the coupling reaction was carried out for 20 minutes. 15.0 mmol of methanol was added to this polymer solution as a reaction terminator, yielding a rubbery polymer solution (XS) before hydrogenation.
A portion of the rubbery polymer solution (XS) before hydrogenation was withdrawn and the solvent was removed in a dryer to obtain a rubbery polymer (X) before hydrogenation.
The analysis results are shown in Table 1.

(Preparation of Rubber Composition)
Example 1 Rubber Composition (SH-1)
To the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) was added the hydrogenation catalyst (TC-1) prepared in (Production Example 1) in an amount of 70 ppm based on titanium (140 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 50 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubber-like polymer (S-1). The iodine value of the obtained rubber-like polymer was 85.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (SH-1).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 2.

Example 2 Rubber Composition (SH-2)
To the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) was added the hydrogenation catalyst (TC-1) prepared in (Production Example 1) in an amount of 70 ppm based on titanium (140 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 80 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubber-like polymer (S-2). The iodine value of the obtained rubber-like polymer was 38.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (SH-2).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 2.

Example 3 Rubber Composition (SH-3)
To the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) was added the hydrogenation catalyst (TC-2) prepared in (Production Example 2) in an amount of 80 ppm based on titanium (240 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 50 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubber-like polymer (S-3). The iodine value of the obtained rubber-like polymer was 85.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (SH-3).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 2.

<( Reference Example 4) Rubber Composition (SH-4)>
The hydrogenation catalyst (TC-1) prepared in (Production Example 1) was added to the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) in an amount of, per 100 parts by mass of the rubber-like polymer before hydrogenation,
70 ppm titanium (140 ppm aluminum) added, hydrogen pressure 0.8 MPa
The hydrogenation reaction was carried out for 50 minutes at an average temperature of 85°C to obtain a rubber-like polymer (S-4). The iodine value of the obtained rubber-like polymer was 85.
To the resulting rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then the rubber composition solution 60
The solvent was removed from 100 g of the rubber composition by the method described in the above <Solvent Removal Condition 2>, and the rubber composition was dried in a dryer to obtain a rubber composition (SH-4).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 2.

<( Reference Example 5) Rubber Composition (SH-5)>
The hydrogenation catalyst (TC-1) prepared in (Production Example 1) was added to the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) in an amount of, per 100 parts by mass of the rubber-like polymer before hydrogenation,
55 ppm based on titanium (110 ppm based on aluminum) was added, and the hydrogenation catalyst (TC-3) prepared in Production Example 3 above was further added in an amount of 55 ppm based on titanium per 100 parts by mass of the rubber-like polymer before hydrogenation. A hydrogenation reaction was carried out for 40 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 95°C, yielding a rubber-like polymer (S-5). The iodine value of the resulting rubber-like polymer was 85.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (SH-5).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 2.

Example 6 Rubber Composition (SH-6)
To the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) was added the hydrogenation catalyst (TC-2) prepared in (Production Example 2) in an amount of 70 ppm based on titanium (210 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 50 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubber-like polymer (S-6). The iodine value of the obtained rubber-like polymer was 85.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 3> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (SH-6).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 2.

<( Reference Example 7) Rubber Composition (SH-7)>
The hydrogenation catalyst (TC-1) prepared in (Production Example 1) was added to the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) in an amount of, per 100 parts by mass of the rubber-like polymer before hydrogenation,
20 ppm based on titanium (40 ppm based on aluminum) was added, and the hydrogenation catalyst (TC-3) prepared in Production Example 3 above was further added in an amount of 20 ppm based on titanium per 100 parts by mass of the rubber-like polymer before hydrogenation. A hydrogenation reaction was carried out for 120 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 75°C, yielding a rubber-like polymer (S-7). The iodine value of the resulting rubber-like polymer was 85.
The obtained rubber polymer solution was added with n-octadecyl-3-(3,5-di-
12.6 g of t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added, and then the rubber composition solution 60
The solvent was removed from 100 g of the mixture by the method described in the above <Solvent Removal Condition 2>, and the mixture was dried in a dryer to obtain a rubber composition (SH-7).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 2.

Example 8 Rubber Composition (TH-1)
To the rubber-like polymer solution (TS) before hydrogenation obtained in (Polymerization Example 2) was added the hydrogenation catalyst (TC-1) prepared in (Production Example 1) in an amount of 70 ppm based on titanium (140 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 60 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubber-like polymer (T-1). The iodine value of the obtained rubber-like polymer was 70.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying in a dryer to obtain a rubber composition (TH-1).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 3.

Example 9 Rubber Composition (SH-8)
To the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) was added the hydrogenation catalyst (TC-1) prepared in (Production Example 1) in an amount of 70 ppm based on titanium (140 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 80 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubber-like polymer (S-8). The iodine value of the obtained rubber-like polymer was 38.
To the obtained rubbery polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and at the same time, 150 g of SRAE oil (JOMO Process NC140, manufactured by JX Nippon Oil & Energy Corporation) was added and mixed, and then 6,000 g of the rubber composition solution was subjected to the method of <Solvent Removal Condition 1> above, and dried in a dryer to obtain a rubber composition (SH-8).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 3.

<(Example 10) Rubber Composition (SH-9)>
The hydrogenation catalyst (TC-1) prepared in (Production Example 1) above was added to the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) above in an amount of 40 ppm based on titanium (80 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 100 minutes at a hydrogen pressure of 0.95 MPa and an average temperature of 78°C to obtain a rubber-like polymer (S-9). The iodine value of the obtained rubber-like polymer was 85.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (SH-9).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 3.

Example 11 Rubber Composition (SH-10)
To the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) was added the hydrogenation catalyst (TC-1) prepared in (Production Example 1) in an amount of 70 ppm based on titanium (140 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 50 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubber-like polymer (S-10). The iodine value of the obtained rubber-like polymer was 85.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and 6 g of stearic acid was added at the same time. Then, the solvent was removed from 6,000 g of the rubber composition solution by the method described above in <Solvent Removal Condition 1>, and the solution was dried in a dryer to obtain a rubber composition (SH-10).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 3.

<(Example 12) Rubber Composition (SH-11)>
To the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) was added the hydrogenation catalyst (TC-1) prepared in (Production Example 1) in an amount of 70 ppm based on titanium (140 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 50 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubber-like polymer (S-11). The iodine value of the obtained rubber-like polymer was 85.
To the resulting rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6,000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, and the mixture was dried in a dryer. The mixture was removed in half the time compared to the above (Example 1), and a rubber composition (SH-11) was obtained.
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 3.

<(Example 13) Rubber Composition (TH-2)>
To the rubber-like polymer solution (TS) before hydrogenation obtained in (Polymerization Example 2) was added the hydrogenation catalyst (TC-1) prepared in (Production Example 1) in an amount of 70 ppm based on titanium (140 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 40 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubber-like polymer (T-2). The iodine value of the obtained rubber-like polymer was 129.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (TH-2).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 3.

<( Reference Example 14) Rubber Composition (WH-1)>
The hydrogenation catalyst (TC-1) prepared in (Production Example 1) was added to the rubber-like polymer solution (WS) before hydrogenation obtained in (Polymerization Example 5) in an amount of, per 100 parts by mass of the rubber-like polymer before hydrogenation,
70 ppm based on titanium (140 ppm based on aluminum) was added, and the hydrogenation catalyst (TC-3) prepared in Production Example 3 above was further added in an amount of 90 ppm based on titanium per 100 parts by mass of the rubber-like polymer before hydrogenation. A hydrogenation reaction was carried out for 30 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C, yielding a rubber-like polymer (W-1). The iodine value of the resulting rubber-like polymer was 70.
To the resulting rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and the rubber composition solution was then cooled to 60°C.
The solvent was removed from 100 g of the rubber composition by the method described above under <Solvent Removal Condition 1>, and the rubber composition was dried in a dryer to obtain a rubber composition (WH-1).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 3.

<( Reference Example 15) Rubber Composition (XH-1)>
The rubber-like polymer solution (XS) before hydrogenation obtained in (Polymerization Example 6) was added with the above (Production Example 1).
The hydrogenation catalyst (TC-1) prepared in the above step was added in an amount of 70 ppm based on titanium (140 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and the mixture was heated under a hydrogen pressure of 0.8 M.
The hydrogenation reaction was carried out at 85° C. for 50 minutes at 100 Pa and an average temperature of 85° C. to obtain a rubber-like polymer (X-1).
The resulting rubbery polymer had an iodine value of 85.
The resulting rubber polymer solution was mixed with 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate as an antioxidant and 4,6-
After adding 3.0 g of bis(octylthiomethyl)-o-cresol, rubber composition solution 6
The solvent was removed from 1000 g of the rubber composition by the method described above under <Solvent Removal Condition 1>, and the rubber composition was dried in a dryer to obtain a rubber composition (XH-1).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 3.

<(Comparative Example 1) Rubber Composition (SH-12)>
The hydrogenation catalyst (TC-1) prepared in (Production Example 1) above was added to the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) above in an amount of 150 ppm based on titanium (300 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 40 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 90°C to obtain a rubber-like polymer (S-12). The iodine value of the obtained rubber-like polymer was 85.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (SH-12).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 4.

<(Comparative Example 2) Rubber Composition (SH-13)>
To the rubbery polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) was added the hydrogenation catalyst (TC-3) prepared in (Production Example 3) in an amount of 70 ppm based on titanium per 100 parts by mass of the rubbery polymer before hydrogenation, and a hydrogenation reaction was carried out for 50 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubbery polymer (S-13). The iodine value of the obtained rubbery polymer was 85.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (SH-13).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 4.

<(Comparative Example 3) Rubber Composition (SH-14)>
To the rubber-like polymer solution (SS) before hydrogenation obtained in (Polymerization Example 1) was added the hydrogenation catalyst (TC-1) prepared in (Production Example 1) in an amount of 5 ppm based on titanium (10 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and further the hydrogenation catalyst (TC-3) prepared in (Production Example 3) was added in an amount of 90 ppm based on titanium per 100 parts by mass of the rubber-like polymer, and the hydrogenation reaction was carried out for 40 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 80°C to obtain a rubber-like polymer (S-14). The iodine value of the obtained rubber-like polymer was 85.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 2> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (SH-14).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 4.

<(Comparative Example 4) Rubber Composition (TH-3)>
To the rubber-like polymer solution (TS) before hydrogenation obtained in (Polymerization Example 2) was added the hydrogenation catalyst (TC-1) prepared in (Production Example 1) in an amount of 70 ppm based on titanium (140 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 90 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubber-like polymer (T-3). The iodine value of the obtained rubber-like polymer was 14.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (TH-3).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 4.

<(Comparative Example 5) Rubber Composition (UH-1)>
To the rubbery polymer solution (US) before hydrogenation obtained in (Polymerization Example 3) was added the hydrogenation catalyst (TC-1) prepared in (Production Example 1) in an amount of 70 ppm based on titanium (140 ppm based on aluminum) per 100 parts by mass of the rubbery polymer before hydrogenation, and a hydrogenation reaction was carried out for 60 minutes at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C to obtain a rubbery polymer (U-1). The iodine value of the obtained rubbery polymer was 70.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (UH-1).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 4.

<(Comparative Example 6) Rubber Composition (VH-1)>
To the rubber-like polymer solution (VS) before hydrogenation obtained in (Polymerization Example 4) was added the hydrogenation catalyst (TC-1) prepared in (Production Example 1) in an amount of 70 ppm based on titanium (140 ppm based on aluminum) per 100 parts by mass of the rubber-like polymer before hydrogenation, and a hydrogenation reaction was carried out for 120 minutes at a hydrogen pressure of 0.9 MPa and an average temperature of 85°C to obtain a rubber-like polymer (V-1). The iodine value of the obtained rubber-like polymer was 9.
To the obtained rubber polymer solution, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants, and then 6000 g of the rubber composition solution was subjected to the method described above in <Solvent Removal Condition 1> to remove the solvent, followed by drying treatment in a dryer to obtain a rubber composition (VH-1).
The analysis results and evaluation of the rubber composition and the evaluation of the bale molded article are shown in Table 4.

In Table 1, the modifying agents Compounds 1 to 4 are shown below.
Compound 1: 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane Compound 2: N,N'-(1,4-phenylene)bis(4-(triethoxysilyl)butan-1-imine)
Compound 3: N,N,N',N'-tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine Compound 4: silicon tetrachloride

[Examples 16 to 18] [Comparative Examples 7 to 10]
[Preparation of rubber composition for crosslinking and evaluation of physical properties]
Using the rubber compositions SH-1 to SH-3, SH-12, TH-3, UH-1, and VH-1 of (Examples 1 to 3), (Comparative Example 1), and (Comparative Examples 4 to 6) shown in Tables 2 to 4 as raw rubber components, rubber compositions for crosslinking containing each raw rubber were obtained according to the formulation shown below.

(Rubber component)
Rubber composition (samples: SH-1 to SH-3, SH-12, TH-3, UH-1, VH-1)
: 80 parts by mass (parts by mass excluding rubber softener)
High-cis polybutadiene (trade name "UBEPOL BR150" manufactured by Ube Industries, Ltd.)
:20 parts by mass

(Composition conditions)
The amount of each compounding ingredient added is shown in parts by mass per 100 parts by mass of the rubber component not including the rubber softener.
Silica 1 (trade name "Ultrasil 7000GR" manufactured by Evonik Degussa, nitrogen adsorption specific surface area 170 m/g): 50.0 parts by mass; Silica 2 (trade name "Zeosil Premium 200MP" manufactured by Rhodia, nitrogen adsorption specific surface area 220 m/g): 25.0 parts by mass; Carbon black (trade name "Seat KH (N339)" manufactured by Tokai Carbon Co., Ltd.): 5.0 parts by mass; Silane coupling agent (trade name "Si75" manufactured by Evonik Degussa, bis(triethoxysilylpropyl) disulfide): 6.0 parts by mass; SRAE oil (trade name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation): 25.0 parts by mass; Zinc oxide: 2.5 parts by mass; Stearic acid: 1.0 part by mass. Antioxidant (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 2.0 parts by mass Sulfur: 2.2 parts by mass Vulcanization accelerator 1 (N-cyclohexyl-2-benzothiazylsulfinamide): 1.7 parts by mass Vulcanization accelerator 2 (diphenylguanidine): 2.0 parts by mass Total: 222.4 parts by mass

(Kneading method)
The above materials were kneaded by the following method to obtain a rubber composition.
In the first stage of mixing, raw rubber (samples SH-1 to SH-3, SH-12, TH-3, UH-1, VH-1), fillers (silica 1, silica 2, carbon black), silane coupling agent, SRAE oil, zinc oxide, and stearic acid were kneaded using an internal mixer (internal capacity: 0.3 L) equipped with a temperature control device at a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm.
At this time, the temperature of the internal mixer was controlled so that the discharge temperature was 155 to 160°C, and each rubber composition (compound) was obtained.
Next, in the second stage of kneading, the compound obtained above was cooled to room temperature, and then an antioxidant was added and kneaded again to improve the dispersion of the silica. In this case, the discharge temperature of the compound was adjusted to 155 to 160°C by controlling the temperature of the mixer.
After cooling, the mixture was kneaded in the third stage using an open roll set at 70° C. by adding sulfur and vulcanization accelerators 1 and 2. The mixture was then molded and vulcanized in a vulcanization press at 160° C. for 20 minutes.
The rubber compositions after vulcanization were evaluated, specifically, by the following methods.
The results are shown in Table 5.

(Evaluation 1, 2) Wet skid resistance, fuel economy (viscoelasticity parameters)
The viscoelastic parameters were measured in torsion mode using a viscoelasticity tester "ARES" manufactured by Rheometrics Scientific.
Tan δ measured at 0° C., a frequency of 10 Hz, and a strain of 1% was used as an index of wet skid resistance. A larger index indicates better wet skid resistance.
Tan δ measured at 50° C., a frequency of 10 Hz, and a strain of 3% was used as an index of fuel economy. A smaller index indicates better fuel economy.
In Table 5 below, the physical properties of the compound of Comparative Example 7 are used as the standard, and symbols are given when each property changes within the following ranges.
△: worsened by less than 5% to improved by less than 5%; ○: improved by 5% or more to improved by less than 15%; ⊚: improved by 15% or more to improved by less than 20%; ×: worsened by 5% or more

(Evaluation 3) Breaking Properties Breaking strength and breaking elongation were measured in accordance with the tensile testing method of JIS K 6251. The product of the measured values of breaking strength and breaking elongation was defined as breaking properties.
In Table 5 below, the symbols are given when the properties of each compound vary within the following ranges, based on the physical properties of the compound of Comparative Example 7.
△: worsened by less than 5% to improved by less than 5%; ○: improved by 5% or more to improved by less than 15%; ⊚: improved by 15% or more to improved by less than 20%; ×: worsened by 5% or more

As shown in Tables 2 to 4, it was confirmed that the bale molded products of the rubber compositions of Examples 1 to 15 were superior to the comparative examples in terms of the balance of cold flow properties, mold contamination resistance, heat deterioration resistance, peel resistance of the rubber composition from the molded product, and adhesion of the packaging sheet to the molded product.
The bale molded body is less susceptible to cold flow, which reduces deformation over time and improves the handleability of the bale molded body. Furthermore, the resistance to thermal degradation eliminates heat-induced degradation during production and from production to use, and further reduces degradation during the preparation (kneading) of the crosslinking rubber composition, etc., resulting in good physical properties after processing. The resistance to mold contamination reduces contamination due to materials adhering to the mold during bale molding, resulting in excellent production stability. The resistance to peeling of the rubber composition from the bale molded body reduces the amount of rubber composition peeling after bale molding, resulting in excellent bale moldability and excellent production stability. Furthermore, the ease with which a packaging sheet adheres to the bale molded body reduces the gap between the packaging sheet and the bale, reducing condensation and improving handleability during transportation.
Furthermore, as shown in Table 5, it was confirmed that the rubber compositions for crosslinking in Examples 16 to 18 had a balance of physical properties equal to or better than that of the rubber composition for crosslinking in Comparative Example 7, while the rubber compositions for crosslinking in Comparative Examples 8 to 10 had an inferior balance of physical properties.

The rubber composition that constitutes the bale molded product of the present invention is suitable as a constituent material of a crosslinking composition, and specifically has industrial applicability in fields such as tire components, automobile interior and exterior parts, vibration-proof rubber, belts, footwear, foams, and various industrial product applications.

Claims (7)

a rubbery polymer (A) having an iodine value of 10 to 250, an ethylene structure of 3% by mass or more, and a vinyl aromatic monomer block of less than 10% by mass;
Aluminum (B),
a metal (C) from Group 3 and/or Group 4 of the periodic table;
Contains
40 ppm≦aluminum (B) content≦200 ppm;
The content of metals (C) of Group 3 and/or 4 of the periodic table is 61 ppm or less,
the rubber-like polymer (A) is a hydrogenated product of a conjugated diene polymer, and has a vinyl aromatic monomer unit content of 5% by mass or more, and a modification rate measured by a column adsorption GPC method of 40% by mass or more;
A method for producing a bale molded product of a rubber composition, comprising:
polymerizing the conjugated diene polymer in a solution;
adding aluminum (B) and a metal (C) of Group 3 and/or Group 4 of the periodic table to the solution containing the conjugated diene-based polymer;
thereafter, hydrogenating the conjugated diene-based polymer to obtain the rubber composition containing the rubbery polymer (A) ;
molding the rubber composition;
A method for producing a bale molded body, comprising: The rubber-like polymer (A) contains a nitrogen atom.
A method for producing the bale molded article according to claim 1 . The rubber composition further contains 30% by mass or less of a rubber softener (D).
A method for producing the bale molded article according to claim 1 or 2 . The rubber composition contains water in an amount of 0.05% by mass or more and 1.5% by mass or less.
A method for producing the bale molded article according to any one of claims 1 to 3 . The rubber composition contains lithium in an amount of 2 ppm or more and 60 ppm or less.
A method for producing the bale molded body according to any one of claims 1 to 4 . 90 mass% or more of the aluminum (B) is aluminum oxide and/or aluminum hydroxide.
A method for producing the bale molded body according to any one of claims 1 to 5 . a step of removing the solvent from the solution containing the rubbery polymer (A) by steam stripping;
A method for producing the bale molded body according to any one of claims 1 to 6 .